I live in the U.S. and I pronounce
Clara as claire-ah but I have heard quite a lot of people pronounce it clah-rah so in the US, I'd feel comfortable saying either way is acceptable. I have heard
Lara pronounced both ways as well. Personally, I say lah-rah unless someone with that name specifically tells me to pronounce it lair-ah. I think it really just comes down to your personal preference.